The invention relates to a method for Internet-protocol-based transmission, particularly real-time transmission, of communication data, such as voice, video or multimedia data.
In contemporary communication systems, many types of data are transmitted between data processing devices using the “Internet protocol”—IP for short. With the Internet protocol, data to be transmitted are divided up into data packets which, having each been provided with a destination address identifying a transmission destination, are transmitted to the transmission destination independently of one another. Such data packets are frequently also referred to as Internet protocol datagrams or IP datagrams.
On account of its widespread international use and on account of very low data transmission costs, the Internet protocol is also becoming increasingly important for real-time transmission of communication data. Since the Internet protocol was not designed with a view to real-time applications, however, it has one or two disadvantageous properties for real-time applications. Thus, by way of example, because the Internet protocol datagrams are transmitted independently of one another, the transmission times for the Internet protocol datagrams can fluctuate greatly. In addition, the asynchronous transmission of the Internet protocol datagrams, particularly when there is a high transmission load, means that packet collisions arise which result in delay or in entire Internet protocol datagrams being rejected.
To compensate for transmission time fluctuations, Internet protocol datagrams arriving at a receiver are normally buffer-stored in a buffer, from which they are read at constant time periods. However, buffering the Internet protocol datagrams causes further delay which cannot be tolerated in the case of many real-time applications.